Electrosurgical forceps for grasping, treating, and/or dividing tissue

ABSTRACT

An electrosurgical forceps includes first and second shaft members pivotably coupled to one another via a pivot member such that pivoting of the first and second shaft members between spaced-apart and approximated positions pivots jaw members thereof between open and closed positions. A knife is translatable between retracted and extended positions. A knife deployment mechanism is operably coupled to the first shaft member and includes at least one trigger and at least one linkage coupling the at least one trigger with the knife such that pivoting of the at least one trigger relative to the first shaft member translates the knife between the retracted and extended positions. A knife lockout biased towards a locked position inhibits distal translation of the knife. The knife lockout is movable from the locked position to an unlocked position upon approximation of the jaw members to permit distal translation of the knife.

BACKGROUND

The present disclosure relates to electrosurgical instruments and, more particularly, to electrosurgical forceps for grasping, treating, and/or dividing tissue.

TECHNICAL FIELD

A surgical forceps is a plier-like instrument which relies on mechanical action between its jaws to grasp tissue. Electrosurgical forceps utilize both mechanical clamping action and electrical energy to treat tissue, e.g., coagulate, cauterize, and/or seal tissue.

Typically, once tissue is treated, the surgeon has to accurately sever the treated tissue. Accordingly, many electrosurgical forceps have been designed which incorporate a knife configured to effectively sever tissue after treating the tissue.

SUMMARY

As used herein, the term “distal” refers to the portion that is being described which is further from a surgeon, while the term “proximal” refers to the portion that is being described which is closer to a surgeon. Further, to the extent consistent, any of the aspects described herein may be used in conjunction with any or all of the other aspects described herein.

An electrosurgical forceps provided in accordance with aspects of the present disclosure includes first and second shaft members, a pivot member, a knife, a knife deployment mechanism, and a knife lockout. Each shaft member includes an inner frame, a jaw member secured to and extending distally from the inner frame, and an outer housing surrounding a portion of the inner frame. The pivot member pivotably couples the inner frames of the first and second shaft members to one another such that pivoting of the first and second shaft members relative to one another between spaced-apart and approximated positions pivots the jaw members relative to one another between open and closed positions. The knife is selectively translatable through the first shaft member from a retracted position to an extended position wherein the knife extends at least partially between the jaw members. The knife deployment mechanism is operably coupled to the first shaft member and includes at least one trigger and at least one linkage coupling the at least one trigger with the knife such that pivoting of the at least one trigger relative to the first shaft member translates the knife between the retracted and extended positions. The knife lockout includes a cantilever arm biased towards a locked position inhibiting distal translation of the knife. The cantilever arm is movable from the locked position to an unlocked position upon approximation of the jaw members to permit distal translation of the knife.

In an aspect of the present disclosure, the knife lockout further includes a body and a finger. The body forms a portion of the outer housing of the first shaft member. The cantilever arm extends from the body within the outer housing of the first shaft member. The finger extends from the cantilever arm externally of the outer housing of the first shaft member towards the second shaft member. In the approximated position of the first and second shaft members, the outer housing of the second shaft member is configured to contact the finger and urge the cantilever arm to the unlocked position permitting distal translation of the knife. The cantilever arm, the body, and the finger of the knife lockout may be a single, monolithic component.

In another aspect of the present disclosure, a pivot pin pivotably couples the at least one linkage of the knife deployment mechanism and the knife. In such aspects, in the locked position of the cantilever arm, the pivot pin is captured within a nook defined between the cantilever arm and the finger to inhibit distal translation of the knife.

In another aspect of the present disclosure, the inner frame of the first shaft member includes a body plate, a reinforcing plate secured to the body plate, and a channel defined between the body plate and a reinforcing plate. In such aspects, the knife is slidably disposed within the channel.

In yet another aspect of the present disclosure, the at least one linkage of the knife deployment mechanism includes a first linkage and a second linkage. The first linkage includes at least one boss at a first end portion thereof that engages the at least one trigger with the first linkage. The first linkage is pivotably coupled to a first end portion of the second linkage at a second end portion of the first linkage. The second linkage is pivotably coupled to the knife at a second end portion of the second linkage.

In still another aspect of the present disclosure, the inner frame of the first shaft member defines an aperture through which one of the at least one bosses of the first linkage extends to pivotably couple the first linkage to the first shaft member.

In still yet another aspect of the present disclosure, the first linkage is disposed on one side of the inner frame of the first shaft member and the second linkage is disposed on an opposite side of the inner frame of the first shaft member. Further, the cantilever arm of the knife lockout may be disposed on the same side of the inner frame of the first shaft member as the first linkage.

In another aspect of the present disclosure, the first and second shaft members each further include a handle engaged with a support plate. The support plates are secured within the outer housings of the respective shaft members.

In still another aspect of the present disclosure, a biasing member is operably coupled between the support plate of the first shaft member and the knife deployment mechanism to bias the knife towards the retracted position.

In yet another aspect of the present disclosure, the electrosurgical forceps further includes first and second lead wires, an electrosurgical cable, and a switch assembly. The first and second lead wires extend through the second shaft member and electrically couple to the first and second jaw members, respectively. The electrosurgical cable is coupled to the second shaft member and adapted to connect to a source of electrosurgical energy. The switch assembly is disposed on the second shaft member, includes an activation button, and electrically couples the first and second lead wires, the electrosurgical cable, and the activation button with one another such that actuation of the activation button supplies electrosurgical energy to the first and second jaw members.

In still yet another aspect of the present disclosure, in the approximated position of the first and second shaft members, the first shaft member is configured to actuate the activation button.

In another aspect of the present disclosure, the switch assembly further includes a Printed Circuit Board (PCB) having the activation button mounted on a central portion thereof, the electrosurgical cable electrically coupled to a first end portion thereof, and the first and second lead wires electrically coupled to a second end portion thereof. The switch assembly further includes circuit traces defined on the PCB and electrically coupling the electrosurgical cable, the activation button, and the first and second lead wires with one another.

In still another aspect of the present disclosure, the switch assembly further includes at least one quick-connect receptacle disposed on the PCB at the second end portion thereof. The at least one quick-connect receptacle is configured to facilitate electrical coupling of the first and second lead wires with the PCB.

In another aspect of the present disclosure, the jaw member of the first shaft member includes a jaw support engaged with the inner frame of the first shaft member, and an insulative housing surrounding a portion of the jaw support and extending proximally about a portion of the inner frame of the first shaft member, and an electrically-conductive tissue-contacting plate disposed on the jaw support and partially surrounded by the insulative housing.

In yet another aspect of the present disclosure, the jaw support is secured to the inner frame of the first shaft member and/or the insulative housing is overmolded about the jaw support and the portion of the inner frame of the first shaft member.

In still another aspect of the present disclosure, a proximally-extending portion of the jaw support overlaps the inner frame of the first shaft member and defines a roof configured to receive a distal cutting portion of the knife in the retracted position of the knife.

In another aspect of the present disclosure, the knife extends through a slot defined in the pivot member. Further, the knife may include a stop shoulder inhibited from passing through the slot in the pivot member such that the stop shoulder abuts the pivot member in a distal-most position of the knife, thereby defining the distal-most position of the knife.

In still yet another aspect of the present disclosure, in the approximated position of the first and second shaft members, the at least one trigger is fully disposed within a height dimension of the first and second shaft members such that the at least one trigger does not extend beyond the height dimension of the first and second shaft members.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and features of the present disclosure are described hereinbelow with reference to the drawings wherein like numerals designate identical or corresponding elements in each of the several views:

FIG. 1 is a side, perspective view of an electrosurgical forceps provided in accordance with aspects of the present disclosure;

FIG. 2A is a perspective view from one side of the forceps of FIG. 1 with portions of outer housings of first and second shaft members removed to illustrate the internal components therein;

FIG. 2B is a perspective view from the other side of the forceps of FIG. 1 with other portions of the outer housings of the shaft members removed to illustrate the internal components therein;

FIG. 3A is a perspective view of an inner frame and a jaw member of the first shaft member of the forceps of FIG. 1;

FIG. 3B is an enlarged, side, perspective view of a distal portion of the jaw member of FIG. 3A;

FIG. 3C is perspective view of another body plate of the inner frame and jaw member configured for use with the forceps of FIG. 1;

FIG. 4A is a perspective view of an inner frame and a jaw member of the second shaft member of the forceps of FIG. 1;

FIG. 4B is an enlarged, perspective view of a distal portion of the jaw member of FIG. 4A;

FIG. 5A is a perspective view of a distal portion of the forceps of FIG. 1 illustrating the first and second jaw members pivotably coupled to form the end effector assembly;

FIG. 5B is a transverse, cross-sectional view taken along section line “5B-5B” in FIG. 5A;

FIG. 5C is a first perspective view of a pivot member of the end effector assembly of the forceps of FIG. 1

FIG. 5D is a second perspective view of the pivot member of the end effector assembly of the forceps of FIG. 1;

FIG. 6 is a side, perspective view of the forceps of FIG. 1 with portions removed to illustrate a knife deployment mechanism of the forceps;

FIG. 7 is a rear view of a pair of triggers and a first linkage of the knife deployment mechanism of FIG. 6;

FIG. 8 is a side view of a handle of the first shaft member of the forceps of FIG. 1 shown operably coupled to a first linkage of the knife deployment mechanism of FIG. 6;

FIG. 9 is a side view of a knife of the forceps of FIG. 1;

FIG. 10 is a perspective view of a distal portion of the knife of FIG. 9;

FIG. 11A is an enlarged, side view of a connector end of one of the pair of triggers configured for use with the knife deployment mechanism of FIG. 6;

FIG. 11B is an enlarged, side view of a portion of the outer housing of the first shaft member of the forceps of FIG. 1 including a keyed aperture configured to receive the connector end of the trigger of FIG. 11A;

FIGS. 12A and 12B are enlarged, internal views illustrating rotation of the connector end of the trigger of FIG. 11A within the keyed aperture of the outer housing of the first shaft member of FIG. 11B;

FIG. 13 is a transverse, cross-sectional view illustrating the pair of triggers of FIG. 11A engaged with the outer housing of the first shaft member of FIG. 11B and the knife deployment mechanism of FIG. 6;

FIG. 14 is a side view of a proximal portion of the forceps of FIG. 1 with portions removed to illustrate a knife lockout of the forceps;

FIG. 15 is a rear view of the forceps of FIG. 1;

FIG. 16A is a top, perspective view of a switch assembly of the forceps of FIG. 1;

FIG. 16B is a bottom, perspective view of the switch assembly of FIG. 16A; and

FIGS. 17A-17H illustrate assembly of the forceps of FIG. 1 in accordance with the present disclosure.

DETAILED DESCRIPTION

Referring generally to FIGS. 1-2B, a forceps 100 provided in accordance with the present disclosure includes first and second shaft members 110, 120 each having a proximal end portion 112 a, 122 a and a distal end portion 112 b, 122 b. An end effector assembly 200 of forceps 100 includes first and second jaw members 210, 220 extending from distal end portions 112 b, 122 b of shaft members 110, 120, respectively. Forceps 100 further includes a pivot member 130 pivotably coupling first and second shaft members 110, 120 with one another, a knife 140 (FIGS. 9-10), a knife deployment mechanism 150 for selectively deploying knife 140 (FIGS. 9-10) relative to end effector assembly 200, a knife lockout 170 for inhibiting deployment of knife 140 (FIGS. 9-10) prior to sufficient closure of jaw members 210, 220, and a switch assembly 180 for enabling the selective supply of electrosurgical energy to end effector assembly 100. An electrosurgical cable 300 electrically couples forceps 100 to a source of energy (not shown), e.g., an electrosurgical generator, to enable the supply of electrosurgical energy to jaw members 210, 220 of end effector assembly 200 upon activation of switch assembly 180.

Continuing with reference to FIGS. 1-2B, each shaft member 110, 120 includes an inner frame 114, 124, an outer housing 116, 126 surrounding at least a portion of the respective inner frame 114, 124, and a handle 118, 128 engaged with the respective outer housing 116, 126 towards proximal end portions 112 a, 122 a of shaft members 110, 120, respectively. Inner frames 114, 124 are described in greater detail below. Outer housings 116, 126 enclose and/or operably support the internal components disposed within shaft members 110, 120. More specifically, as detailed below, outer housing 116 of shaft member 110 encloses and supports at least a portion of inner frame 114, knife deployment mechanism 150, and lockout 170, while outer housing 126 of shaft member 120 receives electrosurgical cable 300 and encloses and supports at least a portion of inner frame 124, switch assembly 180, and the lead wires 310 of electrosurgical cable 300. Handles 118, 128 are engaged with outer housings 116, 126 towards proximal end portions 112 a, 112 b of shaft members 110, 120 and extend outwardly from shaft members 110, 120. Handles 118, 128 define finger holes 119, 129 configured to facilitate grasping and manipulating shaft members 110, 120.

Referring to FIG. 3A, inner frame 114 of shaft member 110 includes a body plate 115 a and a reinforcing plate 115 b attached to body plate 115 a, e.g., via welding, to provide increased lateral stiffness and structural support thereto. In embodiments, reinforcing plate 115 b may be welded to body plate 115 a in at least two places, e.g., towards the proximal and distal end portions thereof. The increased lateral stiffness provided by reinforcing plate 115 b helps ensure alignment of depressible button 183 b (FIG. 16A) of switch assembly 180 with outer housing 116 of shaft member 110 (Fig. such that depressible button 183 b is depressed and switch assembly 180 activated upon sufficient approximation of shaft members 110, 120 (see also FIG. 15).

Inner frame 114 defines one or more location apertures 115 c, a trigger aperture 115 d, and a longitudinal slot 115 e that each extend through both body plate 115 a and reinforcing plate 115 b. The one or more location apertures 115 c are configured to receive corresponding posts 117 of outer housing 116 to locate and maintain inner frame 114 in position within outer housing 116. Body plate 115 a extends distally beyond reinforcing plate 115 b to enable attachment of jaw support 212 of jaw member 210 thereto, e.g., via staking or other suitable engagement. The portion of body plate 115 a that extends distally beyond reinforcing plate 115 b further defines a pivot aperture 115 f extending transversely therethrough. A stop protrusion 115 g extends from inner frame 114 into pivot aperture 115 f, as detailed below. Body plate 115 a of inner frame 114 further defines a longitudinal channel 115 h oriented towards reinforcing plate 115 b such that reinforcing plate 115 b encloses a portion of longitudinal channel 115 h.

With additional reference to FIG. 3B, as noted above, jaw support 212 of jaw member 210 is staked or otherwise engaged, e.g., welded, press-fit, mechanically locked, etc., to the portion of body plate 115 a that extends distally beyond reinforcing plate 115 b. Jaw member 210 further includes an electrically-conductive, tissue-contacting plate 214 and an insulative housing 216. Tissue-contacting plate 214 defines a longitudinally-extending knife channel 215 a extending at least partially therethrough and may include one or more stop members 215 b disposed thereon and electrically isolated therefrom. Insulative housing 216 of jaw member 210 is overmolded or otherwise secured about a portion of jaw support 212, tissue-contacting plate 214, and body plate 115 a of inner frame 114 of shaft member 110. Insulative housing 216 includes a distal portion 217 a and a proximal extension portion 217 b. Proximal extension portion 217 b of insulative housing 216 is configured to extend proximally along body plate 115 a of inner frame 114 to (or proximally beyond) pivot aperture 115 f thereof. The electrical lead 310 (FIGS. 2A and 3B) configured to electrically couple to tissue-contacting plate 214 is captured between body plate 115 a and proximal extension portion 217 b of insulative housing 216 to protect and facilitate routing of the electrical lead 310 (FIGS. 2A and 3B) from shaft member 120, around pivot aperture 115 f, and distally therefrom to electrically couple to tissue-contacting plate 214.

Distal portion 217 a of insulative housing 216 of jaw member 210 extends about the periphery of tissue-contacting plate 214 and defines a main section 218 a, a raised section 218 b, and a beak section 218 c. Main section 218 a of distal portion 217 a of insulative housing 216 extends on either side of tissue-contacting plate 214 and is offset relative thereto such that tissue-contacting plate 214 is raised relative to main section 218 a. Raised section 218 b of distal portion 217 a of insulative housing 216 extends distally from main section 218 a on either side of tissue-contacting plate 214 and is still recessed relative to tissue-contacting plate 214 but is closer to being co-planar with tissue-contacting plate 214 as compared to main section 218 a. Beak section 218 c of distal portion 217 a of insulative housing 216 is disposed distally of tissue-contacting plate 214 and extends to or beyond tissue-contacting plate 214. Beak section 218 c inhibits tissue from entering the area between jaw members 210, 220 of end effector assembly 200 when end effector assembly 200 is disposed in the closed position and utilized for blunt dissection (see FIG. 5A).

Referring to FIG. 3C, another embodiment is provided wherein body plate 115 a′ of inner frame 114′ does not define the pivot aperture therethrough but, rather, terminates proximally of the pivot location. In this embodiment, jaw support 212′ of jaw member 210′ defines pivot aperture 115 f′ and extends from the distal body portion of jaw member 210′ proximally beyond the pivot location to enable jaw support 212′ to be staked or otherwise engaged to body plate 115 a′ of inner frame 114′ proximally of the pivot location. Pivot aperture 115 f′ defined within jaw support 212′ receives pivot member 130 similarly as detailed above with regard to pivot aperture 115 f (se FIGS. 3A and 5C). In this embodiment, jaw support 212′ may include, in the areas where jaw support 212′ replaces body plate 115 a (FIG. 3A), any of the features of body plate 115 a of inner frame 114 (see FIG. 3A) and may likewise include any of the features of jaw support 212 (FIG. 3A).

Continuing with reference to FIG. 3C, in embodiments, the jaw support, e.g., jaw support 212′, may further define a notch 115 i′ configured to receive an edge 125 g (FIG. 17B) of distal clevis portion 125 c of inner frame 124 of shaft member 120 (FIG. 4A) therein to define the spaced-apart position of shaft members 110, 120 (see FIGS. 2A-2B). That is, receipt of edge 125 g (FIG. 17B) within notch 115 i′ inhibits further movement of shaft members 110, 120 apart from one another, thus defining the furthest spaced-apart portion of shaft member 110, 120 (see FIGS. 2A-2B).

Turning to FIG. 4A, inner frame 124 of shaft member 120 includes an elongated body portion 125 a, an enlarged proximal portion 125 b, and a distal clevis portion 125 c. Enlarged proximal portion 125 b of inner frame 124 provides additional structural support to shaft member 120 and defines one or more location apertures 125 d that, similarly as with location apertures 115 c of inner frame 114 of shaft member 110 (FIG. 3A), are configured to receive corresponding posts 127 of outer housing 126 to locate and maintain inner frame 124 in position within outer housing 126. Elongated body portion 125 a of inner frame 124 extends through outer housing 126 of shaft member 120, while distal clevis portion 125 c of shaft member 120 extends distally from outer housing 126. Distal clevis portion 125 c may be welded to, monolithically formed with, or otherwise engaged to elongated body portion 125 a of inner frame 124. Distal clevis portion 125 c of inner frame 124 is detailed below.

Elongated body portion 125 a defines a flexibility, e.g., is flexible an amount according to a spring constant thereof, thus enabling flexure of elongated body portion 125 a in response to application of a jaw force at jaw member 220. This configuration enables the application of a jaw force within a particular range, e.g., between about 3 kg/cm² and about 16 kg/cm², when shaft members 110, 120 are disposed in the approximated position corresponding to the closed position of jaw members 210, 220. Referring also to FIGS. 3A, 3B, and 4B, in embodiments, in addition to the flexion of elongated body portion 125 a providing a jaw force within a particular range, flexion of the jaw members 210, 220 may also contribute to providing a jaw force within a particular range. More specifically, due to the relatively fine configuration of the jaw members 210, 220 and the fact that the jaw members 210, 220 taper in height and width from the proximal ends to the distal ends thereof, the jaw members 210, 220 themselves provide flexibility that, in conjunction with the flexibility of elongated body portion 125 a, provide a jaw force within a particular range to facilitate tissue treatment.

Referring to FIGS. 4A and 4B, jaw member 220 of end effector assembly 200 is supported on a distal extension (not shown) of distal clevis portion 125 c of inner frame 124 of shaft member 120. The distal extension (not shown) of distal clevis portion 125 c of inner frame 124 serves as the jaw frame of jaw member 220. Jaw member 220 further includes an electrically-conductive, tissue-contacting plate 224 and an insulative housing 226. Tissue-contacting plate 224 defines a longitudinally-extending knife channel 225 extending at least partially therethrough and may include one or more stop members, similarly as with jaw member 210 (FIG. 3B). Insulative housing 226 of jaw member 220 is similar to that of jaw member 210 (FIG. 3B) and, thus, the features thereof will not be repeated here.

As illustrated in FIGS. 1 and 3A-4B, jaw members 210, 220 taper in height and width from the proximal ends to the distal ends thereof, thus facilitating blunt dissection and inhibiting jaw splay. Jaw members 210, 220 also define curved configurations that facilitate visualization of the surgical site and provide increased surface area for grasping tissue.

With reference to FIGS. 5A-5B, distal clevis portion 125 c of inner frame 124 of shaft member 120 and body plate 115 a of inner frame 114 of shaft member 110 are pivotably coupled to one another via pivot member 130 such that shaft members 110, 120 are movable relative to one another between spaced-apart and approximated positions to thereby pivot jaw members 210, 220 relative to one another between open and closed positions. More specifically, distal clevis portion 125 c and body plate 115 a define a lock-box configuration wherein distal clevis portion 125 c includes a bifurcated, U-shaped configuration having an elongated slot defined therein, and wherein body plate 115 a is configured for nested receipt within the elongated slot of the bifurcated, U-shaped distal clevis portion 125 c. Referring in particular to FIG. 5B, sufficient clearance is provided between distal clevis portion 125 c and body plate 115 a when body plate 115 a is nested within distal clevis portion 125 c such that lead wires 310 are permitted to extend therethrough, ultimately to electrically couple tissue-contacting plates 214, 224 (FIGS. 3B and 4B, respectively) to switch assembly 180 (FIGS. 1-2B) and the source of energy (not shown). Further, body 172 of knife lockout 170 is configured for positioning adjacent body plate 115 a within distal clevis portion 125 c to minimize lateral play between body plate 115 a and distal clevis portion 125 c and to act as a wire guide to maintain the lead wires 310 for jaw member 210 distally spaced-apart from pivot member 130. With respect to acting as a wire guide, body 172 of knife lockout 170 inhibits the lead wire 310 for jaw member 210 from interfering with and being damaged during the pivoting of shaft members 110, 120 about pivot member 130, and inhibits the lead wire 310 for jaw member 210 from interfering with and being damaged by translation of knife 140.

Referring also to FIGS. 5C-5D, pivot member 130 includes a body 132 and a cap 134. Body 132 of pivot member 130 is configured to extend through an aperture 125 e defined through one of the side walls of distal clevis portion 125 c of inner frame 124 of shaft member 120, pivot aperture 115 f of body plate 115 a of inner frame 114 of shaft member 110, and into a keyed aperture (or apertures) 125 f defined through the other side wall of distal clevis portion 125 c in fixed rotational orientation relative thereto. Body portion 132 of pivot member 130 is configured to be welded to the portion of the side wall of distal clevis portion 125 c that surrounds keyed aperture(s) 125 f. More specifically, the keying of body portion 132 within keyed aperture(s) 125 f maintains proper orientation of pivot member 130 during welding. Body 132 is further configured to abut stop protrusion 115 g (FIG. 3A) upon pivoting of shaft members 110, 120 away from one another to define a furthest-spaced apart position of shaft members 110, 120 and, similarly, a most-open position of jaw members 210, 220. A slot 136 defined through body 132 of pivot member 130 is configured to permit translation of knife 140 (FIGS. 9-10) therethrough, as detailed below.

Cap 134 of pivot member 130 defines a location recess 134′ therein, as illustrated in FIG. 5C, for example, although other configurations are also contemplated. Location recess 134′ is described below with respect to the assembly of forceps 100.

Turning to FIGS. 1 and 6-8, knife deployment mechanism 150 is coupled to shaft member 110 and generally includes a pair of opposed triggers 152 extending from either side of shaft member 110, first and second linkages 154, 156, and a biasing spring 158. Knife deployment mechanism 150 is disposed within outer housing 116 of shaft member 110 with the exception of opposed triggers 152 which extend from either side of outer housing 116. First linkage 154 is configured for positioning on one side of inner frame 114 of shaft member 110 and includes a pair of integral (or otherwise engaged) pivot bosses 161 extending from either side thereof at a first end portion of first linkage 154. One of the pivot bosses 161 extends through trigger aperture 115 d of inner frame 114 (see FIG. 3A). Each pivot boss 161 extends through an aperture defined through outer housing 116 of shaft member 110 to enable engagement of opposed triggers 152 therewith on either side of shaft member 110, e.g., via press-fitting, adhesion, or other suitable engagement.

Referring to FIGS. 6-8, a proximal end portion of second linkage 156 is pivotably coupled to first linkage 154 at a second end portion of first linkage 154. However, greater or fewer linkages 154, 156 are also contemplated. A distal end portion of second linkage 156 is pivotably coupled to knife 140 (see also FIGS. 9-10) via a pivot pin 163. Pivot pin 163 may be integrally formed with second linkage 156, e.g., as a post extending therefrom, or may be a separate component from second linkage 156. Pivot pin 163 extends transversely through longitudinal slot 115 e of inner frame 114 of shaft member 114 such that pivot pin 163 is constrained to longitudinal movement within longitudinal slot 115 e. Second linkage 156 is disposed on one side of inner frame 114, which may be the same side as first linkage 154 or the opposite side (as shown). In either configuration, pivot pin 163 extends from second linkage 156 and through longitudinal slot 115 e such that a portion of pivot pin 163 protrudes laterally from the opposite side of inner frame 114.

Biasing spring 158 may be configured as an extension spring or other suitable biasing spring 158 and is engaged at a distal end portion thereof to first linkage 154 and at a proximal end portion thereof to a support plate 166. Support plate 166 includes handle 118 of shaft member 110 integrally formed therewith or otherwise engaged thereto, and may be secured within outer housing 116 in any suitable fashion, e.g., via protrusion-aperture engagement. Support plate 166 provides increased structural support to shaft member 110 to inhibit splaying of shaft members 110, 120 during use. Shaft member 120 similarly includes a support plate 168 integrally formed with or otherwise engaging handle 128 of shaft member 120 and secured to outer housing 126, although support plate 168 need not extend distally as with support plate 166 (see FIGS. 2A and 2B).

Biasing spring 158 biases first linkage 154 towards a first orientation, corresponding to the un-actuated position of triggers 152 and the proximal-most position of second linkage 156, thereby biasing knife 140 towards the retracted position. Upon rotation of either of triggers 152 relative to shaft member 110, first linkage 154 is rotated against the bias of biasing spring 158 to thereby urge second linkage 156 distally such that pivot pin 163 is driven distally though longitudinal slot 115 e to urge knife 140 from the retracted position towards an extended position, wherein knife 140 extends through slot 136 of pivot member 130 and channels 215 a, 225 of jaw members 210, 220 (FIGS. 3B and 4B, respectively).

Referring to FIGS. 9 and 10, knife 140 includes a proximal body 142 defining an aperture 144 through which knife 140 is pivotably coupled to second linkage 156 of knife deployment mechanism 150 via pin 163 (see FIG. 6). Proximal body 142 is slidably disposed within channel 115 h between body plate 115 a and reinforcing plate 115 b of inner frame 114 of shaft member 110 (see FIG. 3A). Knife 140 further includes a distal body 146 defining a lower profile as compared to proximal body 142 and extending distally from proximal body 142. Distal body 146 defines a distal cutting portion 148. Distal cutting portion 148 defines an enlarged height as compared to distal body 146 and may be etched to define an asymmetrically sharpened configuration wherein one side of distal cutting portion 148 extends further distally than the opposite side (due to the removal of material from the opposite side during the etching process). The enlarged height of distal cutting portion 148 helps ensure that distal cutting portion 148 extends fully through the gap defined between jaw members 210, 220 (FIG. 1) and is at least partially received in respective knife channels 215 a, 225 thereof (see FIGS. 3B and 4B). In the retracted position of knife 140, the enlarged height of distal cutting portion 148 is configured for receipt within a roof 213 defined by a proximally-extending portion of jaw support 212 of jaw member 210 (see FIG. 3A). The etched distal cutting edge of distal cutting portion 148 defines three segments: a main cutting segment 149 a, a lower cutting segment 149 b extending from one end of main cutting segment 149 a at an angle relative thereto, and an upper cutting segment 149 c extending from the opposite end of main cutting segment 149 a at an angle relative thereto.

Knife 140 further includes a partial etch 149 d extending along a portion of distal body 146 and distal cutting portion 148 of knife 140. Partial etch 149 d may extend along either or both sides of knife 140. Partial etch 149 d is configured to inhibit wear of knife 140, to promote flexibility to facilitate translation of knife 140 through knife channels 215 a, 225 of jaw members 210, 220 (see FIGS. 3A-4B), to facilitate smooth translation of knife 140 through knife channels 215 a, 225 (see FIGS. 3A-4B) should partial etch 149 d come in contact with the sidewalls defining channels 215 a, 225 (see FIGS. 3A-4B), and to provide greater clearance between knife 140 and the sidewalls defining channels 215 a, 225 (see FIGS. 3A-4B).

In use, distal body 146 of knife 140 is configured to reciprocate through slot 136 of pivot member 130 (FIG. 5D) to translate distal cutting edge 148 through knife channels 215 a, 225 of jaw members 210, 220 in response to actuation of either of triggers 152 (see FIGS. 2A-4B). Knife 140 further includes a stop shoulder 147 defined at the transition between proximal body 142 and distal body 146. Stop shoulder 147 defines a height greater than a height of slot 136 of pivot member 130 (FIG. 5D) such that stop shoulder 147 is inhibited from passing therethrough. Accordingly, stop shoulder 147 defines the distal-most extent of travel of knife 140, e.g., wherein stop shoulder 147 abuts pivot member 130 (FIG. 5D). Alternatively, rather than abutting pivot member 130, stop shoulder 147 may abut a portion of distal clevis portion 125 c defining keyed aperture(s) 125 f for similar purposes.

With momentary reference to FIGS. 1 and 2A, knife deployment mechanism 150 is operably positioned on shaft member 110 and relative to shaft member 120 such that such that triggers 152 do not extend beyond the height dimension of forceps 100 in the vicinity of triggers 152, even in the furthest-approximated position of shaft members 110, 120. As a result of this configuration, forceps 100 benefits from a low-profile design that inhibits triggers 152 from catching on the surgeon, patient, or on nearby objections during use and/or as forceps 100 is inserted and withdrawn from the surgical site.

Referring to FIGS. 11A-13, in some embodiments, each trigger 152′ may be provided with a non-circular aperture 153 a′ configured to receive a correspondingly-shaped pivot boss (not shown) of first linkage 154′ (FIG. 13). In such embodiments, each trigger 152′ may further include a pair of opposed cantilever arms 153 b′ extending from opposite sides of non-circular aperture 153 a′. As detailed below, cantilever arms 153 b′ include fingers 153 c′ configured to operably engage outer housing 116′ to retain triggers 152′ in engagement with first linkage 154′ (FIG. 13) without the need for press-fitting.

With reference to FIG. 11B, in order to operably engage triggers 152′, outer housing 116′ defines a pair of opposed apertures 118′ (only one of which is shown) defining a pair of cut-outs 119 a′. Outer housing 116′ further includes a stop protrusion 119 b′ on an inner surface thereof adjacent each cut-out 119 a′.

Referring to FIGS. 12A and 12B, in order to engage triggers 152′ with outer housing 116′, triggers 152′ are oriented such that non-circular apertures 153 a′ are aligned relative to the correspondingly-shaped pivot bosses (not shown) and such that cantilever arms 153 b′ are aligned relative to cut-outs 119 a′. Thereafter, triggers 152′ are advanced such that the pivot bosses (not shown) are received within non-circular apertures 153 a′ and such that cantilever arms 153 b′ extend sufficiently through cut-outs 119 a′ and into outer housing 116′ such that fingers 153 c′ are disposed internally of outer housing 116′. Once this position has been achieved, triggers 152′ are rotated relative to outer housing 126 such that fingers 153 c′ are no longer aligned with cut-outs 129 a′ and, accordingly, such that triggers 152′ are inhibited from backing out of apertures 128′. Thereafter, first linkage 154′ is coupled to the other components of the knife deployment mechanism, e.g., similarly as detailed above. This engagement of first linkage 154′ with the other components defines a range of motion of first linkage 154′ and, more specifically, limits the range of motion thereof such that, in conjunction with stop protrusions 119 b′, first linkage 154′ inhibits triggers 152′ from rotating back to a position wherein cantilever arms 153 b′ are aligned relative to cut-outs 119 a′. Thus, disengagement of triggers 152′ from outer housing 116′ and first linkage 154′ are inhibited without requiring press-fit, adhesion, or other backout-preventing engagement between triggers 152′ and first linkage 154′.

Turning to FIGS. 1, 2A, and 14, knife lockout 170 works in conjunction with shaft members 110, 120 to inhibit deployment of knife 140 prior to shaft members 110, 120 reaching a sufficiently-approximated position corresponding to a sufficiently-closed position of jaw members 210, 220. Knife lockout 170 includes a body 172 that is disposed about a portion of the inner frame 114 of shaft member 110 and forms a portion of outer housing 116 of shaft member 110. More specifically, as shown in FIG. 1, body 172 of knife lockout 170 defines a complementarily-shaped abutting surface with the abutting surface of the adjacent other component(s) of housing 116 such that housing 116 defines a substantially continuous outer surface. Body 172 extends at least partially within U-shaped distal clevis portion 125 c of shaft member 110 to inhibit excess lateral play therebetween, as noted above.

Referring to FIG. 14, knife lockout 170 further includes a cantilever arm 174 extending proximally from body 172. Cantilever arm 174 and body 172 may be integrally formed, e.g., via injection molding, or may be attached in any other suitable fashion. Cantilever arm 174 extends along inner frame 114 of shaft member 110 on an opposite side of inner frame 114 as compared to second linkage 156 of knife deployment mechanism 150. Cantilever arm 174 defines a relatively narrowed configuration to permit flexing of cantilever arm 174. A finger 176 integrally formed with cantilever arm 174 extends generally perpendicularly from a free end of cantilever arm 174 and through an opening defined in outer housing 116 of shaft member 110 towards shaft member 120. A nook 178 is defined at the junction of cantilever arm 174 and finger 176. A stop 179 protrudes from cantilever arm 174 in the vicinity of nook 178 and defines an angled distal wall 179 a and a vertical proximal wall 179 b that, together with cantilever arm 174 and finger 176, enclose a portion of nook 178.

With shaft members 110, 120 sufficiently spaced-apart from one another, finger 176 of knife lockout 170 is spaced-apart from outer housing 126 of shaft member 120 such that cantilever arm 174 is disposed in its at-rest position. In the at-rest position, cantilever arm 174 extends along and in generally parallel orientation relative to longitudinal slot 115 e of inner frame 114 of shaft member 110. Further, nook 178 is disposed at the proximal end of longitudinal slot 115 e and receives the portion of pivot pin 163 that extends from second linkage 156 through longitudinal slot 115 e therein. As such, vertical proximal wall 179 b of stop 179 inhibits distal advancement of pivot pin 163 in the at-rest position of cantilever arm 174 and, accordingly, inhibits deployment of knife 140.

In order to disengage knife lockout 170 to permit deployment of knife 140, shaft members 110, 120 are sufficiently approximated such that a portion of outer housing 126 of shaft member 120 contacts finger 176 of knife lockout 170 and urges finger 176 further into housing 116 of shaft member 110. As finger 176 is urged further into housing 116, cantilever arm 174 is flexed such that nook 178 is withdrawn from about pivot pin 163 and vertical proximal wall 179 b of stop 179 is removed from the path of pivot pin 163. Once this has been achieved, knife deployment mechanism 150 may be actuated, as detailed above, to advance pivot pin 163 distally through slot 115 e to deploy knife 140 from the retracted position towards the extended position.

Should shaft members 110, 120 be moved apart from one another sufficiently such that shaft member 120 no longer urges finger 176 to flex cantilever arm 174, cantilever arm 174 is resiliently returned to its at-rest position. If knife 140 is disposed in the retracted position at this point, nook 178 is returned to surrounding engagement about pivot pin 163. However, if knife 140 is disposed in the deployed position or a partially-deployed position, the return of cantilever arm 174 to its at-rest position does not re-capture pivot pin 163. Rather, upon subsequent return of knife 140 to the retracted position, pivot pin 163 is moved proximally and into contact with angled distal wall 179 a of stop 179, camming therealong and urging cantilever arm 174 to flex from the at-rest position sufficiently so as to enable pivot pin 163 to return to the proximal end of longitudinal slot 115 e. Once pivot pin 163 reaches this position, cantilever arm 174 is returned to the at-rest position and, as a result, nook 178 is returned to surrounding engagement about pivot pin 163, thereby locking-out knife 140 until shaft members 110, 120 are once again sufficiently approximated. The biasing force of biasing member 158 is sufficient to move pivot pin 163 proximally to deflect cantilever arm 174 and reset knife lockout 170 as detailed above. As such, resetting of knife lockout 170 occurs automatically (if shaft members 110, 120 are sufficiently spaced-apart) upon return of knife 140 to the retracted position.

With reference to FIGS. 2A, 3B, 3A, 4A, and 15, the above-detailed structural support features of shaft members 110, 120 inhibit splaying of shaft members 110, 120 during use, e.g., in the directions of arrows “S” (FIG. 15). More specifically, reinforcing plate 115 b of inner frame 114, enlarged body portion 125 a of inner frame 124, support plates 166, 168 (that retain handles 118, 128), and the lockbox configuration of shaft members 110, 120 all add structural support to shaft members 110, 120 to inhibit splaying of shaft members 110, 120 during use. Further, the positioning of knife 140 within channel 115 h between body plate 115 a and reinforcing plate 115 b inhibits splay of knife 140 during use.

Turning to FIGS. 16A and 16B, switch assembly 180 is disposed on shaft member 120 and generally includes an activation button 182 and a Printed Circuit Board (PCB) 184. Activation button 182 includes a button housing 183 a and a depressible button 183 b. Depressible button 183 b is configured to be contacted by the outer housing 116 of shaft member 110 upon sufficient approximation of shaft members 110, 120 so as to depress depressible button 183 b and activate switch assembly 180. With additional reference to FIGS. 1-2B, as noted above, the position of shaft members 110, 120 wherein switch assembly 180 is activated, together with the flexion of inner frame 124, enable application of a particular jaw force, or jaw force within a particular range, to tissue grasped between jaw members 210, 220.

PCB 184 of switch assembly 180 includes a board body 185 defining a first end portion 186 a, a second end portion 186 b, and a central portion 186 c. Central portion 186 c of board body 185 is configured to receive activation button 182 thereon. More specifically, central portion 186 c defines apertures 187 a (or other suitable engagement features) to enable snap-fitting (or other suitable mechanical engagement) of activation button 182 thereon. Central portion 186 c further defines circuit traces 187 b such that, upon mechanical engagement of activation button 182 thereon, activation button 182 is also electrically coupled to PCB 184. This configuration facilitates assembly and reduces the possibility of improper connections. Circuit traces 187 b extend from central portion 186 c towards first end portion 186 a of board body 185 on both the upper and lower faces of board body 185 to enable connection of a pair of lead wires 310 (only one of which is shown) of electrosurgical cable 300 thereto, e.g., via soldering. Circuit traces 187 b also extend from central portion 186 c towards second end portion 186 b of board body 185 on both the upper and lower faces of board body 185. A quick-connect receptacle 188 is disposed on each of the upper and lower faces of body board 185 towards second end portion 186 b thereof in electrical communication with circuit traces 187 b. Quick-connect receptacles 188 facilitate engagement of lead wire receptacles 189 (only one of which is shown) therewith, thus facilitating coupling of the lead wires 310 of jaw members 210, 220 with switch assembly 180. More specifically, lead wire receptacles 189 are configured to slide into snap fit or other suitable engagement with quick-connect receptacles 188 to both mechanically engage lead wire receptacles 189 with PCB 184 and electrically couple the lead wires 310 of jaw members 210, 220 to corresponding portions of circuit traces 187 b. As a result of the above-detailed configuration of switch assembly 180, activation of activation button 182 initiates the supply of energy from the energy source (not shown) to jaw members 210, 220 such that such energy may be conducted through tissue grasped between tissue-contacting plates 214, 224 of jaw members 210, 220 to treat tissue (see FIGS. 3A-4B).

Referring to FIGS. 17A-17H, the assembly of forceps 100 is detailed. In detailing the assembly of forceps 100 hereinbelow, additional structural features and functional benefits of forceps 100 may be described and/or become apparent. Accordingly, despite being described in connection with the assembly of forceps 100, the features of forceps 100 detailed herein (above or below) are not limited to assembly in the manner detailed below. Likewise, the advantageous order and manner of assembly of the components of forceps 100 as detailed below is not limited to use with the particular features of the various components of forceps 100 detailed above or otherwise herein.

With initial reference to FIGS. 17A and 17B, inner frames 114, 124 of shaft members 110, 120 are pre-assembled with the respective jaw members 210, 220 thereon, as detailed above. Switch assembly 180 is also pre-assembled together with electrosurgical cable 300, as also detailed above. With inner frames 114, 124 pre-assembled with jaw members 210, 220, respectively, knife 140 may then be operably coupled to inner frame 114 of shaft member 110 such that knife 140 extends through longitudinal channel 115 h of inner frame 114 and aperture 144 of knife 140 is aligned with longitudinal slot 115 e of inner frame 114. Thereafter, shaft members 110, 120 are aligned to enable pivot member 130 to be inserted through aperture 125 e of distal clevis portion 125 c of inner frame 124, pivot aperture 115 f of body plate 115 a of inner frame 114, and into keyed aperture(s) 125 f defined through the other side wall of distal clevis portion 125 c. Upon such positioning, slot 136 of pivot member 130 receives a portion of knife 140. Body portion 132 of pivot member 130 may be welded, e.g., via laser welding, to the portion of the side wall of distal clevis portion 125 c that surrounds keyed aperture(s) 125 f at this point or later on during the assembly process. Location recess 134′ of cap 134 of pivot member 130 (see FIG. 5C) is utilized during welding of pivot member 130 to distal clevis portion 125 c, obviating the need to utilize a vision system to enable precise welding. Location recess 134′ further serves as a “zero” position during component assembly, welding (as mentioned above in addition to other welding) and other fixation, and testing, e.g., jaw force testing, jaw gap testing, and electrical testing.

Turning to FIG. 17C, with inner frames 114, 124 of shaft members 110, 120 operably coupled to one another via pivot member 130 and with knife 140 operably coupled to inner frame 114, a portion of outer housing 126 of shaft member 120 is positioned on inner frame 124 and the lead wires 310 of jaw members 210, 220 are routed therethrough. Once routed through the portion of outer housing 126 installed on inner frame 124, the lead wires 310 of jaw members 210, 220 are operably coupled to switch assembly 180 via connection of lead wire receptacles 189 with quick-connect receptacles 188 of switch assembly 180, thereby electrically coupling jaw members 210, 220 with switch assembly 180 and electrosurgical cable 300. Additionally, at this point, knife lockout 170 is installed on inner frame 114 of shaft member 110.

With reference to FIG. 17D, handles 118, 128 are engaged within first half-housing portions of outer housings 116, 126 of shaft members 110, 120, respectively, although handles 118, 128 may alternatively be pre-assembled with the first half-housing portions of outer housing 116, 126. First linkage 154 of knife deployment mechanism 150 is then operably positioned such that one of the pivot bosses 161 thereof extends through a corresponding aperture defined through the first half-housing portion of outer housing 116. Thereafter, biasing member 158 is operably coupled between first linkage 154 and handle 118, as detailed above. The trigger 152 corresponding to the first half-housing portion of outer housing 116 is also engaged about the portion of the pivot boss 161 that extends outwardly from the first half-housing portion of outer housing 116.

Referring to FIG. 17E, the subassembly of FIG. 17C and the subassembly of FIG. 17D are combined. More specifically, inner frames 114, 124 are operable engaged within the respective first half-housing portions of outer housing 116, 126. Further, switch assembly 180 and the distal end of electrosurgical cable 300 are seated within the first half-housing portion of outer housing 126 of shaft member 120.

Turning to FIG. 17F, once the subassemblies of FIGS. 17C and 17D are combined as noted above, second linkage 156 of knife deployment assembly 150 is engaged to first linkage 154 and knife 140 (through inner frame 114 of shaft member 110). With the internal components of forceps 100 in place, the second half-housing portions of outer housing 116, 126 are moved into place to fully form outer housings 116, 126 and enclose the internal components therein, as illustrated in FIG. 17G. Finally, as shown in FIG. 17H, the other trigger 152 of knife deployment mechanism 150 is engaged with the corresponding pivot boss 161 of first linkage 154 on the second half-housing side of outer housing 116 of shaft member 110.

Once assembly is completed, e.g., as detailed above, testing may be performed to ensure proper operation of forceps 100. Such testing may include jaw force testing; testing using a gauge pin (not shown) to test the maximum jaw aperture between jaw members 210, 220 at the distal tips thereof; cut testing of the knife 140 using cut test media (not shown); testing of the gap distance between the tissue-contacting plates 214, 224 of jaw members 210, 220 (as set by the one or more stop members 215 b and/or beak sections 218 c of jaw members 210, 220) in the approximated position thereof at various positions along the lengths of jaw members 210, 220; and/or performing electrical continuity testing.

Referring to FIG. 17H, forceps 100, once fully assembled, defines a first length “L1” extending distally from the midpoint of pivot member 130 to the distal tip of jaw members 210, 220 (FIG. 1) of end effector assembly 200 and a second length “L2” extending proximally from the midpoint of pivot member 130 to the midpoint of handles 118, 128. A ratio L2:L1 of the second length to the first length is from about 2.0 to about 4.0 to provide the surgeon witan expected feel. More specifically, a ratio L2:L1 ranging from about 2.0 to about 4.0 has been found to correspond to an expected feel such that when a surgeon pivots handles 118, 128 towards or away from one another, jaw members 210, 220 (FIG. 1) are pivoted relative to one another an expected amount or close thereto. Ratios outside this range may require that the surgeon learn the device to achieve desired movement of the jaw members 210, 220 (FIG. 1), whereas forceps 100 provides an expected feel without the need for, or minimal, learning. As an example without limitation, length L1 may be about 4 cm and length L2 may be about 14 cm, thereby providing a ratio L2:L1 of 3.5.

The various embodiments disclosed herein may also be configured to work with robotic surgical systems and what is commonly referred to as “Telesurgery.” Such systems employ various robotic elements to assist the surgeon and allow remote operation (or partial remote operation) of surgical instrumentation. Various robotic arms, gears, cams, pulleys, electric and mechanical motors, etc. may be employed for this purpose and may be designed with a robotic surgical system to assist the surgeon during the course of an operation or treatment. Such robotic systems may include remotely steerable systems, automatically flexible surgical systems, remotely flexible surgical systems, remotely articulating surgical systems, wireless surgical systems, modular or selectively configurable remotely operated surgical systems, etc.

The robotic surgical systems may be employed with one or more consoles that are next to the operating theater or located in a remote location. In this instance, one team of surgeons or nurses may prep the patient for surgery and configure the robotic surgical system with one or more of the instruments disclosed herein while another surgeon (or group of surgeons) remotely control the instruments via the robotic surgical system. As can be appreciated, a highly skilled surgeon may perform multiple operations in multiple locations without leaving his/her remote console which can be both economically advantageous and a benefit to the patient or a series of patients.

The robotic arms of the surgical system are typically coupled to a pair of master handles by a controller. The handles can be moved by the surgeon to produce a corresponding movement of the working ends of any type of surgical instrument (e.g., end effectors, graspers, knifes, scissors, etc.) which may complement the use of one or more of the embodiments described herein. The movement of the master handles may be scaled so that the working ends have a corresponding movement that is different, smaller or larger, than the movement performed by the operating hands of the surgeon. The scale factor or gearing ratio may be adjustable so that the operator can control the resolution of the working ends of the surgical instrument(s).

The master handles may include various sensors to provide feedback to the surgeon relating to various tissue parameters or conditions, e.g., tissue resistance due to manipulation, cutting or otherwise treating, pressure by the instrument onto the tissue, tissue temperature, tissue impedance, etc. As can be appreciated, such sensors provide the surgeon with enhanced tactile feedback simulating actual operating conditions. The master handles may also include a variety of different actuators for delicate tissue manipulation or treatment further enhancing the surgeon's ability to mimic actual operating conditions.

From the foregoing and with reference to the various figure drawings, those skilled in the art will appreciate that certain modifications can also be made to the present disclosure without departing from the scope of the same. While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. 

What is claimed is:
 1. An electrosurgical forceps, comprising: first and second shaft members each including an inner frame, a jaw member secured to and extending distally from the inner frame, and an outer housing surrounding a portion of the inner frame, the jaw member of the first shaft member including a jaw support engaged with the inner frame of the first shaft member; an insulative housing surrounding a portion of the jaw support and extending proximally about a portion of the inner frame of the first shaft member; a pivot member pivotably coupling the inner frames of the first and second shaft members to one another such that pivoting of the first and second shaft members relative to one another between spaced-apart and approximated positions pivots the jaw members relative to one another between open and closed positions; a knife selectively translatable through the first shaft member from a retracted position to an extended position wherein the knife extends at least partially between the jaw members; a knife deployment mechanism operably coupled to the first shaft member, the knife deployment mechanism including at least one trigger and at least one linkage coupling the at least one trigger with the knife such that pivoting of the at least one trigger relative to the first shaft member translates the knife between the retracted and extended positions; and a knife lockout including a cantilever arm biased towards a locked position inhibiting distal translation of the knife, the cantilever arm movable upon approximation of the jaw members from the locked position to an unlocked position to permit distal translation of the knife, the knife lockout including a finger extending from the cantilever arm, the finger defining a nook including a proximal wall and a distal wall, wherein, in the locked position of the cantilever arm, a pivot pin of the knife is received between the proximal wall and the distal wall of the nook to prevent distal translation of the knife.
 2. The electrosurgical forceps according to claim 1, wherein the knife lockout further includes a body, the body forming a portion of the outer housing of the first shaft member, the cantilever arm extending from the body within the outer housing of the first shaft member, and the finger extending from the cantilever arm externally of the outer housing of the first shaft member towards the second shaft member, wherein, in the approximated position of the first and second shaft members, the outer housing of the second shaft member is configured to contact the finger and urge the cantilever arm to the unlocked position permitting distal translation of the knife.
 3. The electro surgical forceps according to claim 2, wherein the cantilever arm, the body, and the finger of the knife lockout are a single, monolithic component.
 4. The electrosurgical forceps according to claim 1, wherein the pivot pin pivotably couples the at least one linkage of the knife deployment mechanism and the knife.
 5. The electro surgical forceps according to claim 1, wherein the inner frame of the first shaft member includes a body plate, a reinforcing plate secured to the body plate, and a channel defined between the body plate and a reinforcing plate, and wherein the knife is slidably disposed within the channel.
 6. The electrosurgical forceps according to claim 1, wherein the at least one linkage of the knife deployment mechanism includes a first linkage and a second linkage, the first linkage including at least one boss at a first end portion thereof, the at least one boss engaging the at least one trigger with the first linkage, the first linkage pivotably coupled to a first end portion of the second linkage at a second end portion of the first linkage, the second linkage pivotably coupled to the knife at a second end portion of the second linkage.
 7. The electro surgical forceps according to claim 6, wherein the inner frame of the first shaft member defines an aperture, and wherein one of the at least one bosses of the first linkage extends through the aperture to pivotably couple the first linkage to the first shaft member.
 8. The electro surgical forceps according to claim 6, wherein the first linkage is disposed on one side of the inner frame of the first shaft member, and wherein the second linkage is disposed on an opposite side of the inner frame of the first shaft member.
 9. The electrosurgical forceps according to claim 8, wherein the cantilever arm of the knife lockout is disposed on a same side of the inner frame of the first shaft member as the first linkage.
 10. The electrosurgical forceps according to claim 1, wherein the first and second shaft members each further include a handle engaged with a support plate, each support plate secured within the outer housing of the respective shaft member.
 11. The electrosurgical forceps according to claim 10, wherein a biasing member is operably coupled between the support plate of the first shaft member and the knife deployment mechanism to bias the knife towards the retracted position.
 12. The electrosurgical forceps according to claim 1, further comprising: first and second lead wires extending through the second shaft member, the first and second lead wires electrically coupled to the first and second jaw members, respectively; an electrosurgical cable coupled to the second shaft member and adapted to connect to a source of electrosurgical energy; and a switch assembly disposed on the second shaft member, the switch assembly including an activation button and electrically coupling the first and second lead wires, the electrosurgical cable, and the activation button with one another such that actuation of the activation button supplies electrosurgical energy to the first and second jaw members.
 13. The electrosurgical forceps according to claim 12, wherein in the approximated position of the first and second shaft members, the first shaft member is configured to actuate the activation button.
 14. The electrosurgical forceps according to claim 12, wherein the switch assembly further includes a PCB having the activation button mounted on a central portion thereof, the electrosurgical cable electrically coupled to a first end portion thereof, and the first and second lead wires electrically coupled to a second end portion thereof, and the switch assembly further includes circuit traces defined on the PCB and electrically coupling the electrosurgical cable, the activation button, and the first and second lead wires with one another.
 15. The electrosurgical forceps according to claim 14, wherein the switch assembly further includes at least one quick-connect receptacle disposed on the PCB at the second end portion thereof, the at least one quick-connect receptacle configured to facilitate electrical coupling of the first and second lead wires with the PCB.
 16. The electrosurgical forceps according to claim 1, wherein an electrically-conductive tissue-contacting plate is disposed on the jaw support and partially surrounded by the insulative housing.
 17. The electrosurgical forceps according to claim 16, wherein the jaw support is secured to the inner frame of the first shaft member and wherein the insulative housing is overmolded about the jaw support and the portion of the inner frame of the first shaft member.
 18. The electrosurgical forceps according to claim 16, wherein a proximally-extending portion of the jaw support overlaps the inner frame of the first shaft member and defines a roof configured to receive a distal cutting portion of the knife in the retracted position of the knife.
 19. The electrosurgical forceps according to claim 1, wherein the knife extends through a slot defined in the pivot member, and wherein the knife includes a stop shoulder inhibited from passing through the slot in the pivot member, the stop shoulder configured to abut the pivot member to define a distal-most position of the knife.
 20. The electrosurgical forceps according to claim 1 wherein, in the approximated position of the first and second shaft members, the at least one trigger is fully disposed within a height dimension of the first and second shaft members such that the at least one trigger does not extend beyond the height dimension of the first and second shaft members. 